Optical Spectral Variability of the Very High Energy Gamma-Ray Blazar 1es 1011+496

Böttcher, M.; Hivick, B.; Dashti, J.; Fultz, K.; Gupta, S.; Gusbar, C.; Joshi, M.; Lamerato, A.; Peery, T.; Principe, David A.; Rajasingam, Akshayan; Roustazadeh, P.; Shields, J. C.

doi:10.1088/0004-637x/725/2/2344

Cited by 18 publications

(21 citation statements)

References 18 publications

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“…The results are given in Table 2, the numbering of the stars follows that of Böttcher et al (2010). The derived magnitudes are in good agreement with those in Böttcher et al (2010), deviating typically by less than 2 σ. The source has shown strong variability ever since the beginning of the monitoring, as can be seen from the long-term optical light curve in Fig.…”

Section: Kva Telescope and The Tuorla Blazar Monitoring Programsupporting

confidence: 58%

Multi-Wavelength Observations of the Blazar 1ES 1011+496 in Spring 2008

Ahnen

Ansoldi

Antonelli

et al. 2016

Mon. Not. R. Astron. Soc.

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The BL Lac object 1ES 1011+496 was discovered at Very High Energy (VHE, E>100GeV) γ-rays by MAGIC in spring 2007. Before that the source was little studied in different wavelengths. Therefore a multi-wavelength (MWL) campaign was organized in spring 2008. Along MAGIC, the MWL campaign included the Metsähovi radio observatory, Bell and KVA optical telescopes and the Swift and AGILE satellites. MAGIC observations span from March to May, 2008 for a total of 27.9 hours, of which 19.4 hours remained after quality cuts. The light curve showed no significant variability yielding an integral flux above 200 GeV of (1.3 ± 0.3) × 10 −11 photons cm −2 s −1 . The differential VHE spectrum could be described with a power-law function with a spectral index of 3.3 ± 0.4. Both results were similar to those obtained during the discovery. Swift XRT observations revealed an X-ray flare, characterized by a harder-when-brighter trend, as is typical for high synchrotron peak BL Lac objects (HBL). Strong optical variability was found during the campaign, but no conclusion on the connection between the optical and VHE γ-ray bands could be drawn. The contemporaneous SED shows a synchrotron dominated source, unlike concluded in previous work based on nonsimultaneous data, and is well described by a standard one-zone synchrotron self-Compton model. We also performed a study on the source classification. While the optical and X-ray data taken during our campaign show typical characteristics of an HBL, we suggest, based on archival data, that 1ES 1011+496 is actually a borderline case between intermediate and high synchrotron peak frequency BL Lac objects.

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Section: Kva Telescope and The Tuorla Blazar Monitoring Programsupporting

confidence: 58%

Multi-Wavelength Observations of the Blazar 1ES 1011+496 in Spring 2008

Ahnen

Ansoldi

Antonelli

et al. 2016

Mon. Not. R. Astron. Soc.

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“…In this work, we analyzed the simultaneous multiwavelength spectrum of the source and obtained the broadband SED during three different epochs. The observed SEDs over these epochs clearly show a trend of the synchrotron peak moving to higher energies during increased flux states, similar to the "bluer when brighter" trend seen by Böttcher et al (2010) during 5 years of optical observations of this source. However, Böttcher et al (2010) attributed the observed variability primarily due to magnetic field changes in the jet, whereas our broadband spectral modelling results indicate the spectral behaviour is dominated by changes in the particle spectrum.…”

Section: Discussionsupporting

confidence: 69%

“…This source has been detected in the 0.1 − 300 GeV band by Fermi-LAT, and in the 0.3 − 10 keV band by Swift-XRT (Abdo et al 2010). A detailed study of its optical spectral variability has been done by Böttcher et al (2010). Results of multiwavelength campaigns carried in 2008 (Ahnen et al 2016b) and 2011(Aleksić et al 2016) have recently been published by the MAGIC collaboration.…”

Section: Introductionmentioning

confidence: 99%

On the Spectral Curvature of VHE Blazar 1ES 1011+496: Effect of Spatial Particle Diffusion

Sinha

Sahayanathan

Acharya

et al. 2017

ApJ

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A detailed multi-epoch study of the broadband spectral behaviour of the very high energy (VHE) source, 1ES 1011+496, provides us with valuable information regarding the underlying particle distribution. Simultaneous observations of the source at optical/ UV/ X-ray/ γ-ray during three different epochs, as obtained from Swift-UVOT/ Swift-XRT/ Fermi-LAT, are supplemented with the information available from the VHE telescope array, HAGAR. The longterm flux variability at the Fermi-LAT energies is clearly found to be lognormal. It is seen that the broadband spectral energy distribution (SED) of 1ES 1011+496 can be successfully reproduced by synchrotron and synchrotron self Compton emission models. Notably, the observed curvature in the photon spectrum at X-ray energies demands a smooth transition of the underlying particle distribution from a simple power law to a power law with an exponential cutoff or a smooth broken power law distribution, which may possibly arise when the escape of the particles from the main emission region is energy dependent. Specifically, if the particle escape rate is related to its energy as E 0.5 then the observed photon spectrum is consistent with the ones observed during the various epochs.

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“…Also, flux changes in blazars are often associated with spectral variability (e.g. Xue et al 2006;Böttcher et al 2010;Gaur 2014). …”

Section: Introductionmentioning

confidence: 99%

X-ray spectral studies of TeV γ-ray emitting blazars

Wierzcholska

Wagner

2016

Mon. Not. R. Astron. Soc.

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This work is a summary of the X-ray spectral studies of 29 TeV γ-ray emitting blazars observed with Swift/XRT especially focusing on sources for which X-ray regime allows to study the low and the high energy ends of the particle distributions function. Variability studies require simultaneous coverage, ideally sampling different flux states of each source. This is achieved using X-ray observations by disentangling the high-energy end of the synchrotron emission and the low-energy end of the Compton emission, which are produced by the same electron population. We focused on a sample of 29 TeV γ-ray emitting blazars with the best signal-to-noise X-ray observations collected with Swift/XRT in the energy range of 0.3-10 keV during 10 years of Swift/XRT operations. We investigate the X-ray spectral shapes and the effects of different corrections for neutral hydrogen absorption and decompose the synchrotron and inverse Compton components. In the case of 5 sources (3C 66A, S5 0716+714, W Comae, 4C +21.35 and BL Lacertae) a superposition of both components is observed in the X-ray band, permitting simultaneous, time resolved studies of both ends of the electron distribution. The analysis of multi-epoch observations revealed that the break energy of X-ray spectrum varies only by a small factor with flux changes. Flux variability is more pronounced in the synchrotron domain (high-energy end of the electron distribution) than in the Compton domain (low energy end of the electron distribution). The spectral shape of the Compton domain is stable, while the flux of the synchrotron domain is variable. These changes cannot be described by simple variations of the cut-off energy, suggesting that the high-energy end of the electron distribution is not generally well-described by cooling only.

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Optical Spectral Variability of the Very High Energy Gamma-Ray Blazar 1es 1011+496

Cited by 18 publications

References 18 publications

Multi-Wavelength Observations of the Blazar 1ES 1011+496 in Spring 2008

Multi-Wavelength Observations of the Blazar 1ES 1011+496 in Spring 2008

On the Spectral Curvature of VHE Blazar 1ES 1011+496: Effect of Spatial Particle Diffusion

X-ray spectral studies of TeV γ-ray emitting blazars

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